This application relates to a heat pump being utilized to heat water, and wherein the water cycle is provided with a drain line at a position to protect a gas cooler and other components.
Refrigerant cycles are utilized in many applications to heat or cool another fluid. As an example, refrigerant cycles are often utilized to condition air being delivered into an environment. A typical refrigerant cycle includes a compressor compressing a refrigerant, and delivering that refrigerant to a first heat exchanger known as a condenser. In this heat exchanger, the hot refrigerant loses heat to another fluid, and the refrigerant then passes downstream to an expansion device. In the expansion device, the refrigerant is expanded, and then passes to another heat exchanger. In the second heat exchanger, the cooler refrigerant now takes in heat from yet another fluid. The refrigerant passes from this second heat exchanger back to the compressor.
Recently, the assignee of the present invention has developed a system wherein such a refrigerant cycle is operated in a transcritical manner, and utilizing CO2 as a refrigerant. This transcritical refrigerant cycle is utilized to heat a water supply in the first heat exchanger or evaporator.
Water is delivered from a source of water into a storage tank. When additional heated water is needed, the water flows from the storage tank through the gas cooler or first heat exchanger and is heated by the hot refrigerant. The water may then return to the storage tank, and can eventually be moved to a downstream use as desired.
The above-described system has beneficial attributes. However, when this system is utilized in an environment that may be subject to cold temperatures, there is a danger of damage from the water freezing such as when the system is shut down for a period of time.